Add associations between users via invitations

app/models/invitation.rb

@@ -1,6 +1,7 @@
 class Invitation < ApplicationRecord
   # Relations
   belongs_to :user
+  belongs_to :invitee, class_name: "User", foreign_key: 'invited_user_id', optional: true
 
   # Validations
   validates_presence_of :user

app/models/user.rb

@@ -3,6 +3,10 @@ class User < ApplicationRecord
 
   # Relations
   has_many :invitations, dependent: :destroy
+  has_one  :invitation, inverse_of: :invitee, foreign_key: 'invited_user_id'
+  has_one  :inviter, through: :invitation, source: :user
+  has_many :invitees, through: :invitations
+
   has_many :donations, dependent: :nullify
 
   has_one  :lndhub_user, class_name: "LndhubUser", inverse_of: "user",

app/views/admin/invitations/index.html.erb

@@ -38,8 +38,8 @@
             <tr>
               <td class="overflow-ellipsis font-mono"><%= invitation.token %></td>
               <td><%= invitation.used_at.strftime("%Y-%m-%d (%H:%M UTC)") %></td>
-              <td><%= invitation.user.address %></td>
-              <td><%= User.find(invitation.invited_user_id).address %></td>
+              <td><%= link_to invitation.user.address, admin_user_path(invitation.user.address), class: "ks-text-link" %></td>
+              <td><%= link_to invitation.invitee.address, admin_user_path(invitation.invitee.address), class: "ks-text-link" %></td>
             </tr>
           <% end %>
         </tbody>

app/views/admin/users/show.html.erb

@@ -19,7 +19,11 @@
         </tr>
         <tr>
           <th>Invited by</th>
-          <td><%= @inviter ? link_to(@inviter.address, admin_user_path(@inviter.address), class: 'ks-text-link') : "—" %></td>
+          <td>
+          <% if @user.inviter %>
+            <%= link_to @user.inviter.address, admin_user_path(@user.inviter.address), class: 'ks-text-link' %>
+          <% else %>&mdash;<% end %>
+          </td>
         </tr>
       </tbody>
     </table>